Coronary heart disease (CHD) remains the leading cause of death in middle-age. Although epidemiological studies have suggested a protective role of antioxidants for CHD, the results from intervention studies have been disappointing. The broad aim is to seek specific evidence to explain this apparent discrepancy. The specific objective is to investigate the role of oxidative damage to lipids and proteins in the aetiology of coronary heart disease (CHD). This is to be achieved by measuring specific biomarkers of oxidative damage, using a number of novel assays, on stored blood samples derived from a cohort study of over 10,000 people followed up for an average of 7 years. The biomarkers used will include markers of lipid oxidisation (F2-isoprostanes), protein oxidisation (3-chloro-tyrosine), or a combination of lipid and protein oxidation (modified apo-AI and All). The study will use a nested case/control design. Cases will be the 283 members of the cohort who experienced a CHD event (fatal coronary death or non-fatal myocardial infarction) during the follow-up of the cohort. Each case will be matched to two controls who had no CHD event, giving a total sample size of 879.